Bioactive constituents of chinese natural medicines. VI. Moutan cortex. (2): structures and radical scavenging effects of suffruticosides A, B, C, D, and E and galloyl-oxypaeoniflorin

Five paeonol glycosides, suffruticosides A, B, C, D, and E, and a monoterpene glucoside, galloyl-oxypaeoniflorin, were isolated from the glycosidic fraction of Chinese Moutan Cortex, the root cortex of Paeonia suffruticosa Andrews, together with paeonolide, apiopaeonoside, galloyl-paeoniflorin, oxypaeoniflorin, and paeoniflorin. The structures of five suffruticosides and galloyl-oxypaeoniflorin were elucidated on the basis of chemical and physicochemical evidence. Suffruticosides A, B, C, and D, galloyl-oxypaeoniflorin, and galloyl-paeoniflorin exhibited more potent radical scavenging effects than alpha-tocopherol.     

Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. I. Propagation and initiation of the copolymerization of acrylonitrile with styrene copolymer

Copolymerization of acrylonitrile with styrene spontaneously occurred on addition of zinc chloride without addition of any other radical initiator. The composition of the copolymer approached that of strictly alternating copolymer as zinc chloride added to the copolymerization system increased. The significance of the apparent monomer reactivity ratios of this copolymerization system was studied from a kinetic point of view, and it was shown that the monomer sequence distribution is indicated by the apparent monomer reactivity ratios. Further, equations which represent the relation between the apparent monomer reactivity ratios and Q,e values at a given salt concentration were derived. These equations reasonably accounted for the decrease of the apparent monomer reactivity ratios of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride and the behavior of the other acrylonitrile copolymerization systems in the presence of zinc chloride. The initiation step of the spontaneous radical copolymerization of acrylonitrile with styrene in the presence of zinc chloride was explained by a cross-initiation mechanism.     

Synthesis and properties of new crystalline poly(arylene ether nitriles)

Crystalline poly(arylene ether nitrile) could be prepared by the polycondensation of 2,6-dihalobenzonitrile with resorcinol at 200°C in N-methylpyrrolidone in the presence of sodium carbonate. A reaction temperature of at least 200°C was necessary to attain high molecular weight polymer. Spectral data indicated that the polymer had the structure of a poly(meta-phenylene ether) with pendent nitrile groups on every other phenylene unit. Despite this structure, the crystallinity and the crystallization rate of the polymer were greater than those of the corresponding polymer with a para-linked structure. The glass transition temperature and the melting temperature of the polymer were almost the same as those of poly(etheretherketone) (PEEK^TM). A series of other new poly(arylene ether nitriles) were also examined. The polymers derived from 4,4′-biphenol, dihydroxytetra-phenylmethane, dihydroxydiphenylsulfone, and 1,5-isoquinolinediol had high glass transition temperatures. The poly(arylene ether nitriles) exhibited excellent tensile strength compared with the corresponding ketone- or sulfone-containing polymers. Comparing the three different kinds of polymers containing the same bisphenol units, the order of glass transition temperature was found to be sulfone- > nitrile- > ketone-containing polymers, while the order of tensile strength was nitrile- > ketone- > sulfone-containing polymers. The excellent mechanical properties are attributable to dipole-dipole interactions of nitrile groups. © 1993 John Wiley & Sons, Inc.     

The synthesis of isoquinoline alkaloid and its related compounds using alanine derivatives as chiral auxiliaries

Chiral 1-substituted isoquinoline derivatives, which were obtained by the reaction using alanine derivatives as chiral auxiliaries, were transformed to (S)-2,3,9,10,11-pentamethoxyhomoprotoberberine (7) and a synthetic intermediate for O-methylkreysigine (9) in good yields and high stereoselectivity. The corresponding chiral allyl derivative of isoquinoline was transformed to a pyrrolidinoisoquinoline (16) in a highly enantioselective manner.     

Amphotericin B covalent dimers forming sterol-dependent ion-permeable membrane channels

Polyenemacrolides such as amphotericin B (AmB) were thought to assemble together and form an ion channel across plasma membranes. Their antimicrobial activity has been accounted for by this assemblage, whose stability and activity are dependent on sterol constituents of lipid bilayer membranes. The structure of this channel-like assemblage formed in biomembranes has been a target of extensive investigations for a long time. For the first step to this goal, we prepared several AmB dimers with various linkers and tested for their channel-forming activity. Among these, AmB dimers that bore an aminoalkyl-dicarboxylate tether covalently linked between amino groups of AmB showed potent hemolytic activity. Furthermore, K+ influx actions monitored by measuring the pH of the liposome lumen by 31P NMR revealed that the dimers formed the molecular assemblage similar to that of AmB in phospholipid membrane. Judging from changes in 31P NMR spectra, the dimers appeared to induce "all-or-none"-type ion flux across the liposome membrane in the presence of ergosterol, which suggested that the ion channel formed by ergosterol/dimer is similar to that of AmB. With these data in hand, we are now trying to elucidate the structure of the ion-channel complex by making the labeled conjugates of AmB for NMR measurements.     

Radiation-induced emission from golden hamster embryo cells

Emission from high-energy-electron-irradiated golden hamster embryo (GHE) cells has been studied over the temperature range 12–300 K both by a one-shot-single-photon-counting method and by photocurrent measurements with an oscilloscope. Emission from the irradiated phosphate buffered saline (PBS) also has been studied. The emission spectra from PBS at 12 and 77 K show a maximum around 330 and 380 nm, respectively, which are the same spectra as those from irradiated pure H₂O. The emission from irradiated GHE consists of the new band at 480 nm in addition to the emission from H₂O. The 480 nm emission is observed at the temperature range of 12–300 K, though the emission at 300 K is much lower than that at low temperature. The 480 nm emission is ascribed to the transition from excited organic substances in GHE cells. The intensity of 480 nm emission at 300 K increases linearly with increasing irradiation-dose in the range of 11–600 Gy.     

Synthesis of crowded triarylphosphines carrying functional sites

4,4′-Diphosphinobiaryls and 1,3- and 1,4-borylphosphinobenzenes carrying crowded triarylphosphine moieties were synthesized by reaction of the corresponding diarylchlorophosphine with an arylcopper(I) reagent. Intramolecular interaction of the phosphorus redox center with the other phosphorus or the boron redox center was investigated by cyclic voltammetry. 4,4′-Diphosphinobiaryls displayed two-step reversible redox waves with slight differences of the oxidation potentials due to weak interaction between two phosphorus redox centers across 4,4′-biarylene linkage. Borylphosphinobenzenes showed two step redox waves corresponding to oxidation at the phosphorus and reduction at the boron. Although significant interaction between the phosphorus and boron redox centers was not observed in the cyclic voltammograms due to large difference of the redox potentials between phosphorus and boron redox centers, an absorption due to weakly interacting phosphorus and boron was observed in the UV-Vis spectrum of the 1,4-borylphosphinobenzene.     

Enteric solid dispersion of ciclosporin A (CiA) having potential to deliver CiA into lymphatics

Solid dispersions composed of three components, ciclosporin A (CiA), surfactant (HCO-60) and a pharmaceutical additive, were prepared. As an additive, cellulose acetate phthalate (CAP), methacrylic acid and methacrylic acid methylester copolymer (Eudragit L-100) and hydroxypropylmethylcellulose phthalate (HP-55), which are generally used as enteric coating materials, were employed. The dissolution behavior of CiA from these enteric solid-dispersion system was studied according to the paddle method of JP XI in comparison with that of Sandimmun, an olive oily CiA solution as a reference. Solid dispersion of CiA preparation did not dissolve in the 1st test fluid (pH 1.2) in 2 h. In the 2nd fluid (pH 6.8), about 80% of CiA was dissolved within 12 min, though the dissolution rate was dependent on both the quality and quantity of the additives. An in vivo systemic and lymphatic availability study was performed with rats whose carotid artery and thoracic lymph duct were cannulated. After intrastomach administration of each CiA preparation to rats at a dose of 7 mg/kg, blood and lymph samples were collected for 6 h. One of the HP-55 preparations gave the highest plasma CiA level, Cmax = 0.99 +/- 0.20 (S.E., n = 4) micrograms/ml, and also showed the highest lymphatic availability, the percentage of dose delivered to the lymphatics in 6 h was 1.98 +/- 0.10% and the maximum lymph CiA level was 76.8 +/- 12.86 micrograms/ml. Lymphatic availability of CiA from Sandimmun was 0.78 +/- 0.11% and the peak plasma CiA level was 0.46 +/- 0.10 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bioactive constituents from Chinese natural medicines. XIV. New glycosides of beta-carboline-type alkaloid, neolignan, and phenylpropanoid from Stellaria dichotoma L. var. lanceolata and their antiallergic activities

A new beta-carboline-type alkaloidal glycoside, glucodichotomine B, four new neolignan glycosides, dichotomosides A, B, C, and D, and a new phenylpropanoid glycoside, dichotomoside E, were isolated from a Chinese natural medicine, the roots of Stellaria dichotoma L. var. lanceolata. The structures of the new glycosides were determined on the basis of chemical and physicochemical evidence. Among them, dichotomoside D inhibited the release of beta-hexosaminidase (IC(50)=64 microM) as well as tumor necrosis factor-alpha and interleukin-4 (IC(50)=16, 34 microM) in RBL-2H3 cells. These findings suggest that dichotomoside D is more effective against the late-phase reactions in type I allergy than in the immediate phase.     

Conversion of ammonia to dinitrogen in wastewater by Nitrosomonas europaea

Because Nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen was tried with different reaction conditions. In aerobic reaction conditions, ammonium was converted to nitrite (NO ₂ ⁻ ), while under oxygen-limiting or oxygen-free conditions, NO ₂ ⁻ -N formed from ammonia oxidation by N. europaea was reduced to N₂O and dinitrogen with 22% conversion. During denitrification, optimal pH for the production of N₂O and dinitrogen was found to be 7.0–8.0. Dinitrogen was not produced in acidic pH<7.0. A low partial oxygen pressure as well as oxygen-free conditions are favorable for high production of dinitrogen.